I bring one sheet of paper- my character sheet. I put my character on a custom designed character sheet, editted to fit the particular character, dropping all detail not relevant for that particular character, and dropping everything I can remember on my own. I can generally get a
4e pc on one page up until the paragon tier. I also bring a pen. I write directly on the character sheet, and reprint the character every level after the sheet has been thorougly destroyed.
I also bring my own dice, and a miniature where relevant. I'm the regional painter, so I sometimes bring other people's miniatures, since they're really my miniatures that they're borrowing.
Our group has a rotating system for food and drinks, so I don't bring those unless its my turn.
So that's it, really.
One page character sheet.
Pen.
Dice.
Miniature.
Food if relevant.